Fix custom pulse instruction conversion to Qobj.

[TsafrirA]

Summary

This is a possible fix to #11828.

Details and comments

The behavior of ParametricPulseShapes is restored to raise ValueError when the pulse shape is not supported, and QiskitError when the pulse object is not recognized. The need for the second scenario is not clear to me, but as a quick fix I reverted to the code before #11410.

If we think that the two error types are not needed, we can alternatively change the error type used by the assemble logic.

fixes #11828

[qiskit-bot]

One or more of the the following people are requested to review this:

• @Qiskit/terra-core
• @nkanazawa1989

[coveralls]

Pull Request Test Coverage Report for Build 7964805348

Details

• -1 of 2 (50.0%) changed or added relevant lines in 1 file are covered.
• 5 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.003%) to 89.298%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/qobj/converters/pulse_instruction.py	1	2	50.0%

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	93.81%
crates/qasm2/src/lex.rs	4	91.69%

Totals
Change from base Build 7961815159:	0.003%
Covered Lines:	58906
Relevant Lines:	65966

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💛 - Coveralls

[TsafrirA]

As a side note, I think this bug highlights some deficiencies in the tests. We should probably beef up the tests there, but I didn't want to tie it up with the fix.

[wshanks]

Nice fix, @TsafrirA. I just had some wording suggestions for the release notes.

We are trying to move away from Qobj any way, but it might be worth adding a custom pulse shape to this test or one like it:

qiskit/test/python/compiler/test_assembler.py

Lines 502 to 519 in 12f24a7

	def test_pulse_gates_single_circ(self):
	"""Test that we can add calibrations to circuits."""
	theta = Parameter("theta")
	circ = QuantumCircuit(2)
	circ.h(0)
	circ.append(RxGate(3.14), [0])
	circ.append(RxGate(theta), [1])
	circ = circ.assign_parameters({theta: 3.14})
	with pulse.build() as custom_h_schedule:
	pulse.play(pulse.library.Drag(50, 0.15, 4, 2), pulse.DriveChannel(0))
	with pulse.build() as x180:
	pulse.play(pulse.library.Gaussian(50, 0.2, 5), pulse.DriveChannel(1))
	circ.add_calibration("h", [0], custom_h_schedule)
	circ.add_calibration(RxGate(3.14), [0], x180)
	circ.add_calibration(RxGate(3.14), [1], x180)

[TsafrirA]

Thanks @wshanks! I added a test to cover something like this.

[wshanks]

Looks good!

[nkanazawa1989]

Thanks for the quick fix!